When normal human skin is exposed to an excessive amount of sunlight, there is usually an inflammatory response which can result in erythema, often described as sunburn. This can subsequently lead to peeling of the upper layer of the skin which can detract from the appearance of the skin, particularly with loss of tan, and which can lead to dehydration and more serious damage to the skin.
Treatment of the skin with a sunscreen prior to exposure to sunlight can prevent, or at least limit, erythema. However, if erythema is not limited, sunscreens have little or no effect on subsequent skin peeling (desquamation). Conventional treatment of skin following over-exposure to sunlight usually involves topical application of a moisturiser such as an oil-in-water cream, but this will generally only provide a cooling effect with some relief of the burning and itching sensation that accompanies erythema. Usually it will not prevent peeling of the skin.
It has been proposed in U.S. Pat. No. 4,424,234 (Lever Brothers Company) to provide a cosmetically acceptable aqueous composition for topical application to human skin to provide skin benefit, the composition comprising an hydroxylated C.sub.6 -C.sub.10 carboxylic acid and a cosmetically acceptable vehicle other than water. Among a long list of possible cosmetically acceptable vehicles are sunscreen agents, but there is no suggestion in this reference that the combination of an hydroxylated C.sub.6 -C.sub.10 carboxylic acid together with any specified sunscreen agent can be used in the prevention or treatment of sun-induced desquamation.
Applicants have now discovered, contrary to expectation, that topical application of a composition containing both a 2-hydroxyalkanoic acid, or an ester thereof, and a sunscreen active ingredient can be used in the treatment and/or prevention of sun-induced desquamation.